This invention relates to a method and apparatus for dissolving nickel in molten zinc.
When nickel is added to molten zinc, the dissolution of nickel does not proceed readily. When nickel, which has a relatively high melting point, is added in particulate form to molten zinc, the rate of dissolution is low and a high temperature increment over the melting temperature of the zinc must be provided to increase the rate. In addition, it has been observed that the nickel particulates form semi-plastic masses or agglomerates with the zinc and these masses or agglomerates are slow to dissolve and accumulate in the bottom of the alloying vessel. Efforts to accelerate the dissolution by known methods such as vortex, high-velocity, or high-shear mixing are only partly successful, such mixing often also causing formation of considerable amounts of dross. Dross must not only be removed and treated, but also may contaminate the zinc slabs. Dross formation is aggravated by exposure to oxidizing conditions. As a result of these problems, the zinc slabs containing nickel not only have a relatively large standard deviation from the desired composition specification but sometimes do not meet the specification and must be reprocessed. These problems tend to restrict the process to more costly batch processes.